Reports are flying that Office 2013 may be officially revealed as early as Monday, July 16, when Microsoft tries to keep its most valuable source of revenue relevant to the mobile users it craves and the desktop users it still needs.

According to USA Today and other reports, Microsoft CEO Steve Ballmer is hosting a news conference Monday, where he will announce Office 2013, code-named Office 15, for general availability sometime early next year.

The news itself comes a little later than expected; many pundits were looking for an announcement during Microsoft’s Worldwide Partner Conference in Toronto this week, but no such announcement came. In fact, there was little Office news at all, save for some mentions of Office 365, Microsoft’s cloud-based answer to Google Apps.

It is not clear what Ballmer will be unveiling on Monday, if the published reports are on target, though it’s a good bet that it will be the availability of the first and only public beta for the Office 2013 product.

Mobile or Not Mobile?

As for features, the smart money is on design elements and capabilities that will mesh with Windows 8 and possibly Microsoft’s latest mobile effort, the Microsoft Surface tablet. If that’s the case, Microsoft will need to walk a fine line between ginning up the new version of Office and still making it relevant to the one class of user that seems to be overlooked in all the mobile hype: the average desktop user.

Microsoft can’t get too crazy with the mobile features, because it can’t risk a $22.2 billion business – the largest moneymaker in the company. If Microsoft damages its Office franchise, it would be one of the biggest mistakes in the history of the company. And there is a chance that mistake could happen.

Office Can’t Ignore the Desktop

As mobile gets all the attention and hype, corporate IT managers will be looking very carefully at the new Office to determine if the upgrade is worth it for their fellow employees. If Microsoft oversells the mobile aspects of the new Office, it could risk talking mainstream IT buyers out of upgrading to the new version. Why bother to spend big bucks to upgrade desktop users, after all, if this is all just cool mobile updates? Companies with offices full of nonmobile desktop workers may not need all that.

With that risk in mind, it is unlikely that Microsoft will try to completely change the game with the Office interface, preferring instead to head toward a compromise between a desktop and mobile friendly interface – or possibly even multiple versions for Window 8, Windows 8 RT (the version of Windows 8 for ARM-powered devices, like Microsoft’s upcoming Surface tablet), and maybe even one for Windows 7 and Windows XP.